HOUSTON — Red Sox lefty Matt Thornton felt better Monday after a left oblique issue cropped up a day earlier, but it's not clear yet whether he'll avoid a trip to the disabled list.

"I would say a little better today," Thornton said. "Sore. Doing a whole round of treatment so far, about three to four hours already. Try to do as much as we can to react well and hopefully bounce back tomorrow and feel better. If I show improvement, I could be available in a couple days. But the team comes first, got to make sure I'm available soon."

Another southpaw reliever, Franklin Morales, is scheduled to throw two innings in a rehab outing for Triple-A Pawtucket on Tuesday. Thornton's going for an exam on Tuesday, and whether Morales pitches for Pawtucket could hinge on that exam.

"This is going to be kind of a day-to-day thing for the first couple days," Farrell said, "and then we're going to have to assess where he's at: what the projected time would be to return. If there's any potential roster movement that'll come to a head here in the next couple days.

"(Morales' situation) kind of coincides with Matt. He's scheduled for two (innings) tomorrow ... what we feel, and find out with Matt upon his exam tomorrow, will have a direct impact on (Morales') next outing, how long it is, or where it will be."

Morales (left pectoralis) has thrown three rehab outings for Pawtucket, all of them hitless and scoreless. The last outing 2 1/3 innings on Saturday.

Daniel Nava on paternity leave

Red Sox outfielder Daniel Nava's daughter Faith was born Monday morning. He's on paternity leave through this three-game series with the Astros and is slated rejoin the team on Thursday in Kansas City. Right-hander Brandon Workman, not an outfielder, was recalled from Triple-A Pawtucket in place of Nava.

Red Sox outfielder Shane Victorino was named played of the week in the American League for the week that ended Sunday. He hit .400 (12-for-30) with three doubles, two home runs, and six RBIs as the Sox went 5-2. Mike Napoli and Andrew Bailey were the last Red Sox POW winners, for the week ending April 21.